Fuel-tank size is the spec that decides whether your weekend route is dictated by scenery or by petrol stations. Vietnam’s underbones span a surprisingly wide 3.7-12 litres - all manufacturer figures retrieved 23 September 2026.
The verified tank ladder
CBR150R: 12.0 L. CT125: 5.4 L. Exciter 155 VVA: 5.4 L. Winner R: 4.5 L. Future 125 FI: 4.6 L. Sirius RC: 4.2 L. Wave RSX: 4.0 L. Wave Alpha, Blade, Super Cub C125: 3.7 L each.
Why the CBR150R’s tank is an outlier
Twelve litres on a 150-class bike is a touring decision by Honda: at its published 2.91 L/100 km, the theoretical tank range approaches 410 km - by far the longest of any underbone sold in Vietnam. The trade-offs are 139 kg of mass and the worst economy in the class.
Range = tank x economy
The thriftiest bike (Future 125, 1.47 L/100 km) and the thirstiest (CBR150R) can both deliver the longest usable range in their own way - one by sipping, one by carrying. Our longest-range underbones guide runs the full multiplication for every model.
Practical notes for Vietnam
Most underbones here still run a fuel tap with a reserve position - our fuel-tap guide explains using it before it uses you. And plan rural legs by station density, not just range; the mountain provinces thin out on Sunday evenings. For rental riders, the Wave class (150,000 VND/day, price-published) carries 3.7 litres - fine for the city, plan fuel stops beyond it. Contact us to confirm current availability.